亚洲激情+欧美激情,无码任你躁久久久久久,我的极品美女老婆,性欧美牲交在线视频,亚洲av高清在线一区二区三区

電子課本網(wǎng) › 第75頁(yè)

第75頁(yè)

信息發(fā)布者：
解：因?yàn)?$\frac {1}{x}-\frac {1}{y}=3$?
?$ \frac {1}{x}-\frac {1}{y}=\frac {y-x}{xy}=3$?
所以?$y-x=3xy$?
原式?$=\frac {x-(y-x)-y}{2x+y-x-2y}$?
?$ =\frac {2(x-y)}{x-y}$?
?$ =2$?


D
A
解：原式?$=\frac {a-b}{a-b}×\frac {ab}{a-b}$?
?$ =\frac {ab}{a-b}$?
解：原式?$=\frac {x(x+2)-x(x-2)}{(x-2)(x+2)}×\frac {2-x}{4x}$?
?$ =\frac {4x}{(x+2)(x-2)}×\frac {2-x}{4x}$?
?$ =-\frac {1}{x+2}$?
解：原式?$=1-\frac {a-b}{a+2b}×\frac {(a+2b)2}{(a-b)(a+b)}$?
?$ =1-\frac {a+2b}{a+b}$?
?$ =-\frac {a+b}$?
解：原式?$=\frac {a2-b2+2b2}{a-b}$?
?$ =\frac {a2+b2}{a-b}$?
解：原式?$=\frac {(x-y)2+4xy}{x-y}×\frac {(x+y)2-4xy}{x+y}$?
?$ =\frac {(x+y)2}{x-y}×\frac {(x-y)2}{x+y}$?
?$ =(x+y)(x-y)$?
?$ =x2-y2$
?

解：原式?$=\frac {m+2-(m-2)}{(m+2)(m-2)}$?
?$+\frac {2(m-1)-2(m+1)}{(m+1)(m-1)}$?
?$ =\frac {4}{(m+2)(m-2)}-\frac {4}{(m+1)(m-1)}$?
?$ =\frac {12}{(m+2)(m-2)(m+1)(m-1)}$?
上一頁(yè) 下一頁(yè)